Four-pass hot-blast stove.



J. I. LARIMER.

FOUR-PASS HOT BLAST STQVE. 1,278,173. APPLICATION fILED NOV. 7. 1916- PatentedSept. 10,

5 SHEETS-SHEET 2.

I. LARIMER.

Patented Sept. 10, 1918.

5 SHEETS-SHEE 3.

lzderf MJ 2 ,LVLA 'v J. I. LARIMER.

EOUR-PASS HOT BL'AST STOVE.

1,2787, 173. Paten'd sept. 10,1918. 5 sHEETsfsHEEr 4.

J. I. LARIMER.

FOUR-PASS HOT BLAST STOVE.

APPLICATION FILED Nov. I. 1918.

1 ,278, 1 73 Patented Sept.. 10, 1918.

s sHEETs-sHU s.

Unrrn sms JAMEs I. LARMER, or' JoLrET, ILLINoIs.

FOUR-PASS H'OT-BLAST STOVE.

Specication of Letters Patent.

Patented Sept. 10, 1918.

Application filed November 7, 1916. Serial No. 130,058.

To all 'whom 'it may concer'n:

Be it known that I, J AMEs I. LARIMER, a citizen of the United States, residing at Joliet, in the county of Will and State of Illinois, have invented certain new and useful Improvements in Four-Pass Hot-Blast Stoves, of which the following is a specification.

My invention relates to h'ot blast stoves, and particularly to the form and arrangement of the checkers thereof.

While the stove shown herein is of the four-pass type, many of the features of novelty are applicable to two or three-pass stoves. However, much of the efliciency which has resulted from the use of the stove herein described is present because of its four-pass arrangement.

In the hot blast stoves in common use, the thickness` of the bricks in the checker walls is approximately four inches, making the fiues or checker openings six to nine inches square. The heating surface of such stove is from forty-five thousand to seventy thousand square feet. Using washed blast furnace as for heating, a'stove of the type describe Operating on a blast furnace'of six hundred tons capacity, using about forty thousand cubic feet of wind per minute, will furnish one thousand to twelve hundred Fahrenheit hot blast temperature and with an efficiency of fifty to sixty-five per cent. Of the heat lost, twenty to thirty-five per cent. will be in the escaping stack gases, the balance in radiation, etc.

The minimum number of stoves with which it is possible to loperate a furnace is two, because one of the stoves must have gas burning in it to produce the heat, while the other is furnishing hot blast for the furnace operation. 2It has, however, been the practice heretofore to employ fourv or more stoves. By Operating with maximum efficiency, due to a more scientific arrangement of the checkerwork, fiue areas and decreased division wall areas with resultant increased'heating surface, I have demonstrated itto be possible to operate with two stoves. I have secured an operating efliciency of eighty-five per cent. Such efficiency is only possible in a stove of such construction as to insure relatively great heating surface area, with the elimination of faulty distribution of combustible gases and blast, characteristic of stoves not equipped with my ,improvements It has heretofore been considered eminently desirable to pro- ,vide this great radiating surface in one stove, but no practical means has been suggested whereby it might 'be secured. However, with the advent of washed and purified gas for heating purposes, it has been possible to restrict the size of the flue openings and consequently increase the heating surface. I have, however, designed a construction in which I have provided for the use of bricks' of 2 inches or less. Recognizing, however, that the' greater proportion of fiue 'dust deposit is made in the first pass following the combustion Chamber, I have varied the size of the fiues and thickness of bricksin the three passes following the first pass; that is, the fiues are made successively smaller and the bricks thinner from the second tO the fourth pass.

Not onlv have I' varied the size of the fiue openings, but I have provided at the top of the second pass and at the bottom of the third pass, a by-pass arrangement whereby clogged fiues are short-circuited, any tendency toward channeling is obviated and a redistribution of the'gas may take place. Recognizing that much of the valuable space in a stove has heretofore been occu ied by division walls which had but little eat 'exchange value, I have sov arranged my passes as to require a minimum amount of waste space which is occupi'ed by such walls. By this means I have materially reduced the possibility of distortion of the checkerwork by expansion of such walls.

Furthermore, I have recognized1 the high heat exchange value of metal for checkers and have at the end of the fourth pass provided such metallic checkers. At'this point the variations in heat are not extreme and thev may be 4safely employed. w

Furthermore, in order to avoid exeessive radiation losses, I have insulated the metal shell of the stove from the brick lining. In

this way my losses through radiation are niaterially reduced.

By introducing` the air blast in the bottoin of the fourth pass through one or more inlet pipes and proiecting the air blast toward the bottom of the stove, produce a more uniform and rcduced velocity of air blast through the Checker passage` eliminating the destructive weai'ing action on the brickwork and increasing the etficiency of heat transfer.

nasmuch as the eiiiciency of the stove is so great, I employ means for inducing a draft and am, therefore, able to utilize a small stack, which need be only of suiiicient size to carry the waste gases clear ,of the ground level and working platform.

The invention will be more readily understo'od by reference to the a'ccompanying drawings, wherein- Figure 1 is a Vertical section through a four-pass blast furnace stove constructed in accordance with my invention;

Fig. 2 is a transverse sectional view on the line of Fig, 1;

Fig. 3 is a fragmentary longitudinal sectional view on 'the line 8 8 of Fig. 2;

Fig. -1 is a fragmentary enlarged elevation of the metal checkers which I prefer to empley;

Fig. 5 is a plan view thereof;

Fig. 6 is a fragmentary perspective view showing a novel form of checker arrangement which I employ only in certain portions of the checkers;

Fig. 7 is a similar view showing` the Checker construction in the remainder of the stove. and

Fig. 8 is a Vertical sectional view taken at right angles to Fig. 1.

n the drawings, it will be seen that the stove is surrounded by a metal shell 10 and is mounted upon suitable piers 11. The brick lining 12 of the shell is separated from the metal shell by the use of a quantity of loose insulating material 13. I have found that by suitably insulating the stove at this point a considerable heat saving is effected. 1While it is not es'sentiai, I may prefer to employ bricks composed of insulating material in the wall 12.

It will be noted that the stove is of the four-pass 'type and I have lettered the passes A, B, C, Da respectively in their order, A. being the first or bui'nmg pass.

One of the principal objects in the proposed construction is to provide for a material reduction in eXtent of the division walls which serve to divide the passes. In so doing` the extent of checkers and of heating surface may be increased correspondingly. To this end I provide oval walls 1a. 15.. substa-ntially syininetrically disposed'on diametrically opposite sides of the stove and which in association with the outer wall of the stove serve to define the first and fourth passes respectively of the stove. This leaves a large space,which is generally -shaped in cross section and to form passes B and C, I inerely eXtend a short division wall 16 on the line of the short axes of the first and fourth passes, or, in other words, at the point of shortest distance between the 'two walls 14%, 15. rhus the four passes are divided off with av minimum of Yaste of material and space.

As heretofore explained, it is possible, by the use of washcd and cleaned gas for combustion purposes to inaterially restrict the size of the fiues and consequently increase the area useful for heat exchange; furthermore, that the deposition of fiue dust and residue decreases progressirely from the second to the fouifh passes. To that end, therefore, it will be noted that I have so designed the bricks in the stove that the checker openings are progressively smaller. As a practical installation I have found that Checker opcnings flirt-1% may be employed in the second pass, openings --"x-lf' in the third pass, and opening's 3X3 in the fourth pass. It is understood that do not confine my design to above diinensions in the respective passes7 as the fine openings may be, where the size of shell or other conditions require it B--"X-.lf' in the second pass, 3X3" in the third pass. -jf'x in the fourth pass or even checkerwork of sinaller size. The difference in size of Checker openings is attempted to be shown in Fig. 2.

However, I have found that the tendency to clog the checkers and interfere with the free passage or good distribution of gases therethrough inay be overcome even with the employment of small fiues by a provision such as illustrated in Figs. 1 and 3, and in detail in Fig. 6. As shown in these figures, I provide at the bottom of the third pass and at the top of the second pass, a brick arrangement which permits of by-passing of the gases. As shown in Fig. 6, each aiternate brick of the rows which extend in one direction is eliminated., thereby providing diagonal channels, which have iettered 17.77 As seen in Fig. 1, there is provided an open channel which extends from side to side of the checkers, along the dotted line, which i have marked 17 in that figure. Thus, if the fiues or checkers at one side of the pass become clogged to a certain extent. the gases may by-pass and fiow through other fiues which have not become fouled. In the stove of the stated capacity. I pi'efer to construct the top twelve feet of the second pass and the bottoin twelve feet of the third pass in this nianner41x althoug'h this form of by-pass checker may also bc inserted inidway between |the bottom and top of the Checker passes if desirable. The standard checker construction, as shown in Fig. 7, provides straight rectangular flues 18.

It will be noted that I have arranged the bricks in end-to-end abutting relation. Experience has shown 'tha't if lthe bricks are laid in any other manner the expansion and contraction will cause individual bricks to move outof position and block the opening.

At the lower end of the fourth pass, I have modified the standard construction to a material extent.. In view of the increased area and arrangement of passes, etc., I am able to effect more' complete heat transference, and, therefore, the combustion gases as they emerge into the stack outlet 19, are much cooler thaIi in common practice heretofore. I am, therefore, enabled'to employ a relatively large quantity of metal, the use of which heretofore has been impractical, due to its relatively high co-efficient of eX- pansion. Metal at `this point is desirable, `not only because of its adaptability to efficient heat transference, but because of its stability under the' force of the incoming cold blast. It will be noted, by reference to f Fig. 1, that I have supported the checkerwork of the pass D by means of metal beams 20, which reStupon the arches 21. The arches are in turn faced at their lower sides by means of metal arches 22. Piers 23 support the arches 21, these piers at their lower ends being covered by metal castings 24. Just above the Stack' Outlet 19 are the metal checkers, shown in detail in Figs. 4

and 5. .The checkers are supported upon metal 9beanls 25 and consist of a plurality of boXes having transverse webs 26, the boxes being placed in close relation, alternate, Vertical courses thereof being placed at right angles to each other, thereby forming a multitude of Vertical metallic fiues of Very small cross section. By providing the cut-out portion 27 the ga'ses. are permitted to by-pass as necessary. In Fig. 2 the metal checkers are shown in plan view, only two thereof being shown in detail, however, due to the multitude ofv fine lines which would be required to 'show the entire area in that manner. The cold blast is caused to enter at one ormore points and to be directed 'downwardly by the pipe 28, shown in full lines in Fig. 1 and in dotted lines in Fig. 2. j p

Inoperation a mixture of gas and air is ignitedin the opening 29 and combustion occurs in the pass A. The gases pass downward through pass B, upward through pass C, then'downward through pass D and out at the stack opening 19. Upon reversal, the cold blast enters the pipes 28 and passes in reverse order through the stove.

Obviously the construction is only typical and may be modified 'in many particulars,

all without departure from the spirit of my invention.

I claim:

1. In a four-pass hot blast stove, the combination of walls outlining the first and fourth passes, said passes being substantially symmetrically disposed on diametrically opposite sides of the stove, and a wall bisec'ting the remaining space and serving to form the second and third passes, substantially as descrbed.

2. In a four-pass hot blast stove, the ccmbination of a circular shell outlining the stove, curved walls, the ends of which join said Shell and form with said Shell the first and fourth passes, and a Vertical division Wall joining said curved walls at the point of shortest distance between said walls, substantially as descrbed.

3. In a hot blast stove, the combination of bricks arranged to form checkers in aplurality of the passes and metal shapes arranged to form checkers near the outlet from the last pass.

In a hot blast stove, the combination of a plurality of passes, brick checkerwork in said passes, metal checkerwork near the outlet from the last pass, the flue openinvs in the several passes and in the metal chec ers being successively smaller, substantially as described. i

5-. In a hot blast stove, the combination of a plurality of passes, checkerwork therein, metal checkerwork in the last pass, and a plurality of cold blast entrance openings.

6. In a hot blast stove, the combination of a plurality of passes, checkerwork therein, metal checkerwork in the her. mss, and a plurality of cold blast entrance' openings,

and means associated with said entrance openings for directingl the cold blast away from. the checkers, substantially as described.

` 7. In a four-pass hot blast stove, the combination of checkers located ad'jacentv to the' cold blast inlet point, and a pair' of cold blast entrance elbows located one'at 'each side of the waste gas outlet and arranged to direct the cold blast downwardly and away from said checkers, substantially as descrbed.

. 8.`l In a hot blast stove, the combination of -brick checkerwork and metal checkerwork,

the latter being located near the end of the lastpass, said metal checkerwork being composed of a plurality of associated checker units, each unit providing a plurality of relatlvely small passages through which the gasesmay travel..

. 9. In a hot blast stove, the combination of brick checkerwork and metalcheckerwork,

the latter being located near the end of the.

last pass, said metal checkerwork being composed, of a plurality of associated checker units, each unit being cnposed of a pluplumity of spaee 'webs preving narrow w raliy of spaced Webs previding narrow ver- Vertcal passages, Vertically adjacent units ticel passages. being relativey anguer'ly dspesed;

10. n a hot blast stove, the combination Signe at Chicago, llnoie, :this 3rd day of brek eheckerwork and metal checkerof November, 1916.

Work, the letter being located near the end JAMES LARMER of the last pass, smd metal checkerwork be- Wvtnessesr ng composed of a phlrahty of assoemted LC. F. MURRAYj Checker units, each unit being composed ef a T, D. B'UTLER. 

